In recent years, demands for the cost reduction of the rotation detectors that are applied to the two-wheeled vehicles are increasing. Accordingly, there is a tendency in which the rotation detecting portions are switched from the magnetic detecting elements such as Hall ICs and so on to cheaper magnetic responsive elements such as reed switches or the like.
A known rotation detection devices includes a sensor for detecting a rotation speed of vehicle wheels. The sensor for detecting the rotation speed of the vehicle wheel is provided relative to an outer race rotatably supporting a hub unitary rotating with the wheel. Here the moulding has to be performed after determining positions of the cover member and a body of the sensor relative to a moulding type for the insert moulding. Because the different sizes and the different configurations of the cover member require different dies, the construction of the known rotation detection sensor is not efficient for multi-product production. Thus there exists for a rotation device which is applicable to cover members with different sizes and configurations.
Other known prior art rotation detector in a two-wheeled vehicle are formed by disposing a magnetic detecting element and a magnet, both of which are mounted on a circuit board, to a substantially cylindrical resin case having a detection surface for detecting a detecting object. The rotation detector is attached to a mission case or a sprocket cover and a tooth point. When a tooth point of a mission gear or sprocket is detected with such the rotation detector as a detecting object, since there is a little clearance in the detecting object, the object is caused to vibrate owing to a body stiffness, an engine displacement or the like of a vehicle (two-wheeled vehicle), and a detection position gap between the detecting object and the rotation detector may result in fluctuating. This generates a magnetic fluctuation in the rotation detector and resultantly becomes detection noise. Accordingly, there is a problem in that an indicator for displaying, for instance, a speed corresponding to an output data that is output from the rotation detector may wrongly operate.
Further, the shape and the size of the object for detection are varied according to the kind of vehicle and therefore, it is necessary to adjust the gap for detection between the object for detection and the rotation detector which complicates the integrating operation performance.
Other rotors as described in the prior arts is made our of plastic resin magnet material (Plasto ferrite) and radially magnetized with plurality of poles and mounted on the metal tubular insert. The rotor is inserted into the slots of the hub so that it gets rotated as the hub rotates that is the rotors is synchronized with wheel rotation. The “Magnetic detecting portion” or “Magnetic detecting devise” or “Magnetic conversion element” which is inserted into the hosing comprises reed switch, hall Ics, MR elements or like and electronic circuit to detect the change in magnetic poles of the above said rotor as it rotates.
Prior art also describes rotors that is mounted on a tubular metal insert and rotor's lateral movement is arrested at one side only by the housing wall, but on the other side no such arrangements provided. It is feared that the rotor may falls out from the housing during vehicle assembly or in the field during vehicle service.
The prior art also describes a Circuit board which comprises of predetermined wiring pattern and a “Magnetic detecting portion” or “Magnetic detecting devise” or “Magnetic conversion element” and electronic components and like are electrically connected and fixed by soldering, also with a wire cord to connect with source. Said circuit board along with wire cord is inserted into a groove provided in housing and sealed with a sealing member of epoxy or like. Sealing with epoxy is time consuming and laborious operation. Also handling of circuit board during the manufacturing is difficult as the wire strands soldered with Circuit board will get disturbed and may lead to broken of electrical connection between wires and circuit board. Also rectification of non-functional product is very difficult during manufacturing as the circuit board sealed with epoxy, which is difficult to remove.
In the other existing devices, it is not possible to exchange the circuit board with “Magnetic detecting portion” or “Magnetic detecting devise” or “Magnetic conversion element” in case of malfunctioning or failure of the electronic parts or the wire cord, which is more likely to get damaged during wheel removing or in the field use. One has to replace the complete set of the speed-sensing device in case of above explained situation as the detecting devise is sealed with epoxy, which cannot be serviceable in the field.
The prior art describes about the tubular portion is insert molded with Housing. As the insert molding operation is having low yield of manufacturing thus cost of the product will be significantly high.
There are some related prior patents which include U.S. Pat. No. 6,400,135 which discloses a mounting for a wheel-revolution sensor in the wheel support of a motor vehicle for scanning a revolving pole ring on a wheel comprises an insert which passes through a bore in the wheel support which receives the sensor in an ideal position with respect to the pole ring. Importantly, this prior art relates to inductive type sensor mounted inside a hole in the wheel mounting base and in particular on a plastic housing over the axle of a vehicle wheel. U.S. Pat. No. 6,422,657 is directed to an improved vehicle wheel hub mounting system includes a wheel hub, an axle spindle, a bearing assembly, and a threaded fastener. This invention describes about the mounting arrangement of a Vehicle wheel. U.S. Pat. No. 5,544,962 is again directed to the wheel bearing with arrangement for speed sensor. U.S. Pat. No. 4,075,520 describes about the method of mounting of a speed sensor. A tubular housing with internal snap lock arrangement provided to hold the sensor. U.S. Pat. No. 6,155,114 is directed to the packaging and processing method of a speed sensor. In U.S. Pat. No. 5,920,193 only method of fixing a speed sensor with wheel bearing dust cap for Four wheeler application is taught. Further, WO 00 218878 and WO 9749995 provides for speed sensors which are limited in application and are suitable only for four wheeler applications.
Based on the above state of the art, it is now desirable to provide a Speed Governor for automobiles which will avoid the problems/disadvantages noted above and overcome other problems encountered in conventional speed sensor devices/methods.